Flask



FIG. 1 is front elevational view of the flask showing our new design;

FIG. 2 is a right side elevation thereof, the left side elevation being a mirror image thereof;

FIG. 3 is a perspective view thereof;

FIG. 4 is a top plan view thereof; and,

FIG. 5 is a bottom plan view of our design. 

The ornamental design for a flask, as shown. 